SquareWear 2.0 a Wearable Opensource Arduino

Are you guys tired of redesigned Arduinos yet? Usually we are, but [Ray] just released the SquareWear 2.0, and we have to admit, it’s a pretty slick design.

It’s an update to SquareWear 1.1 which we covered a year ago. That version made use of a 18F14K50 microcontroller, measured a tiny 1.6″ x 1.6″ and could easily be sewn into wearable circuits. But after receiving lots of requests to design a new Arduino based board, [Ray] obliged and made v2.0.

The new SquareWear is slightly bigger, measuring in at 1.7″ x 1.7″, but it packs a much bigger and more functional punch — just check out the image schematic above! The only catch is it doesn’t actually have a USB-to-serial chip on-board, which is why [Ray] was able to get the board so small and inexpensive. Instead it simulates USB in the software using the V-USB library. That method is much slower but still functional. To perform serial communication through the USB port it uses the onboard USBasp bootloader.

The board also features large through-holes to accommodate sew-able pin pads, making it super easy to integrate this into fabric!

For a complete explanation of the SquareWear 2.0, check out the video after the break.

A single LED isn’t going to produce nearly enough heat to produce a noticeable difference in temperature in the area. Especially if it’s used as a wearable, at which point temperature accuracy pretty much goes out the window.

Well, you can still turn off the LED when taking temperature measurement, then turn if back on. It only takes a few milliseconds to get an analog reading, so the LED will look like it’s continuously on. Also, as I said, you can always use PWM to dim the LED. At 3-5mA the LED will look sufficiently bright, and will not dissipate much heat at all. At any rate, the drift caused by the LED is probably not much more than the error / accuracy of the temperature sensor anyways.

For 99% of cases it’s gonna be “98.6” anyway. A human body should generate more heat than an LED, and I doubt the LED would need to run bright for it’s purpose. When it’s on at all. Which won’t be often on a watch battery.

How come these wearable designs never have worthwhile ESD protection? I’d think if any board is going to get zapped, it’s one that’s attached to the front of a constantly moving piece of cloth. Has anyone had such problems with a wearable design, or am I worried about a nonissue?

ESD is both less and more of a concern in wearables simply by the high path loss in conductive threads but made more concerning by the same threads needing “more gain ” etc.
MY suggested “Best Practices” always have involved Optoisolaton or potted transformers etc outside of intrinsically protected things. Protection is a “pays for itself” expense category.

Yeah- you may “get away wit it” x times… but the cost of prevention Vs replacement is likely a no brainer over time.

Optoisolators don’t protect you from ESD, you need special ESD devices for that.

My suggestion is to only use it with cotton fabrics and don’t ever stop dancing (so you’re always a bit damp).

PS: I didn’t want to like this board (yet another overpriced Arduino variant, yawn!) but I do, especially the built-in battery charger system. It totally *destroys* the Lilypad (and for the same price as just the Lilypad main board with no accessories!)

Hate to say this, it doesn’t take a whole lot of experience to “design” (like copy/paste)
an “Arduino” board. It take far less than understand ESD protection and
how it affects layout and and not simply springle “ESD protection” parts
on the board.

By “Optoisolation” in this context – there’s a realistic threat assessment to evaluate. One could for example have photosensors on the “expensive” board and a “cheap” board as the at more risk one. Clamp Diodes and ancient yet still valid tech hacks such as gas tubes- often a Neon Lamp is Quite Good Enough to damage control those MOV’s in a layered ESD defense plan.

in a >$300 device one commonly can see stupidly LITTLE attention spent on protection.

Seeing near zero design for ESD in an LED point boards coupled by Crofon plastic fiber etc.

Small board has an LED Driver and battery for Driver so IR/visible gets fibered to sensor on the “expensive” board.

That was my first thought, too, but take another look…if you’re building the sort of thing this is aimed at then it will be FAR cheaper than buying all the parts (and much easier because it’s all on one PCB).

It makes me crazy that all coin cells aren’t rechargeable. Yesterday I was just playing with the Open Hardware Summit badge from 2013 (I didn’t attend so thanks [Andy] for sending me yours!). The source code for the badge states very clearly that the coin cell is good for about 100 page turns…. then? Well, then you throw it away. This is crazy to me.

Mhm i like that it’s based on the 328 chip, but the onboard sensors are kind of…strange… often you want to hide the module completely so the light sensor is sort of odd.Temperature may be semi useful for sensing ambient body heat and the LED is…weird.

If you need certain sensors, like light sensor, to be separated from the board, you can always connect extra sensors to the available pins. The on-board components are useful for learning and beginners, allowing them to dive in and focus on the programming part.

What is standard pin spacing? You mean 0.1″ like a breadboard? This board is never intended to be used on a breadboard. Also the the large pads are designed so you can solder sew-on snaps. They are much larger than 0.1″ pin spacing.

I have no idea why this uses this fake USB hack with V-USB instead of using the proper AVR chip in the first place. That being the ATmega32u4 as found in the Leonardo. It’s SMD, and has real USB built in.